Core retaining means for concrete slab casting forms



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CORE RETATNTNG MEANS FOR CONCRETE SLAB CASTING FORMS 3 Sheets- Sheet l 93 j?! .j Z3

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Filed April 8, 1968 T. w. sHoE 3,524,232`

. o l M Q Nw BN whwmww. @Wig POBERTL. K AHN ATTY Aug. 18, 1970 CORE RETAINING lvHNS FOR CONCRETE SLAB CASTING FORMS Filed April s. 1968 CORE RETAINING MEANS FOR CONCRETE SLAB CASTING FORMS Filed April 8. 1958 T. Wb SHOE Aug. 1'8, 1970 3 Sheets-Sheet 5 Kiga/0 fvzde." wg/a @we '555 BY ATTY 7 ROBERTLKAHN United States Patent Oiiice 3,524,232 Patented Aug. 18, 1970 3,524,232 CORE RETAINING MEANS FOR CONCRETE SLAB CASTING FORMS Theodore W. Shoe, Troy, Ohio, assigner to The Flexicore C0., Inc., Dayton, Ohio, a corporation of New York Filed Apr. 8, 1968, Ser. No. 719,485 Int. Cl. B28b 7/18, 7/32 U.S. Cl. 25-41 7 Claims ABSTRACT OF THE DISCLOSURE The invention provides means for quickly positioning and locking a set of core positioning plates in a casting form during initial steps in connection with casting concrete slabs, the means providing for easy replacement of core positioning plates depending upon a change in core location in a casting form with change in slab transverse dimensions.

This invention relates to core positioning means for casting forms for casting concrete slabs.

Structural concrete slabs are available in many desired lengths and many desired transverse dimensions. As a rule, a slab made in accordance with the present invention will have one or more longitudinal passages throughout the length of a slab. Frequently, such slabs are provided with longitudinal steel reinforcement (tensioned or not). An example of a slab to which this invention pertains is disclosed in United States Pat. No. 2,299,111. Slabs of this general character may be made in lengths up to 50 or 60 feet, thicknesses of from about 4 inches to 9 or more inches and widths from about 8 inches to several feet. Such slabs have at least one longitudinal passage therethrough for improving load-bearing characteristics as well as saving on concrete material. A slab passageway may have a circular or oval cross-section, depending upon the slab thickness and slab width.

As the above identied patent discloses, longitudinal passage may be created during casting by having long, tubular cores displacing concrete mix. Such cores are generally of inflatable textile or plastic material but may also be of metal or similar material.

irrespective of the nature of the core material and the shape of a core in section, such cores do not have sufficient rigidity longitudinally of a core to be self-supporting, particularly during the initial part of the casting operation when the casting form has been filled with mix and is being vibrated to compact the mix and purge air bubbles from the mix. During this portion of the casting process, the buoyancy of a core will cause the core to rise.

As disclosed in the 2,299,111 patent previously identified, a casting form has bulkheads defining the ends of a casting region and has tubular inatable cores (this patent shows two such cores per slab) extending along the length of a casting form. The casting facility including the casting form is provided with a suitable harness for retaining the cores in a predetermined horizontal position at a desired level at spaced intervals along the length of a casting form. As a rule, the core is positioned at intervals of about 18 or 20 inches along the length of a form (the exact distance between adjacent support regions depending upon operating conditions and being wellknown in the art).

The core retaining harness means is retained in position 1n the casting form until after the casting form has been iilled with mix and vibrated. Thereafter, the core retaining harness is removed upwardly from the casting form and the voids in the mix present after the removal of the harness are filled by a screeding operation. During this screeding operation and the resulting curing operation in a hot steam atmosphere, reliance is had upon the stiffness of the mix to resist substantial upward travel of a core due to the buoyancy of such core. While a core may respond somewhat to its tendency to rise in the concrete in the uncured mass of concrete, the amount of such rise, if any, will usually be small (generally not more than about 1A; inch) and for the most part may be compensated for by initially positioning a core a bit lower than desired.

It is evident from the above that removal of the harness must be accomplished speedily to permit a casting form and its contents to be quickly moved into the curing oven.

A casting form of a predetermined width may have a variety of slab sizes cast therein by the simple expedient of controlling the amount of concrete mix supplied to the casting form. The control for a slab length is a function of the distance between bulkheads and is not involved in the present invention. However, a change in slab thickness for a particular casting form will necessarily result in a change in relative position in the casting form of one or more cores and frequently may involve a change in the shape of a core from one having a circular cross-section to one having an .oval cross-section, apart from a possible change in transverse dimensions of a core.

A casting form involves a substantial investmentt of money and because of this, it is desirable that a casting form of definite width should be susceptible for use in the manufacture of slabs of various thicknesses. The harness arrangement disclosed in the 2,299,111 patent previously identified lacks flexibility in connection with the use of a particular size of casting form for a variety of slab thicknesses. The harness arrangement does not lend itself to ready accommodation for different shapes and/ or positioning, of one or more cores. Due to the fact that the core positioning means must be removed quickly, before the mix begins to cure substantially while waiting to get into the steam ovens and due to the fact that labor costs have made it necessary to provide quick positioning of core retaining means in a casting form as well as removal therefrom, it has been found that using the harness disclosed in the 2,299,111 patent is undesirable.

In accordance With the present invention, a novel core positioning plate is provided, there being a separate plate shape for each type of slab to be cast and quick acting simple but effective locking and unlocking means are provided for quick handling of a set of plates. It is understood that as in the harness arrangement referred to in the 2,299,111 patent, the novel core positioning means is provided at desired intervals along the length of a core. ln accordance with the present invention, a simple and effective locking and unlocking means is provided for a number of core positioning plates along the length of a casting form at each side thereof. A single operating locking and unlocking means is applied to a portion of the length of a casting form on one side thereof so that one workman can operate on a portion of the entire length of casting form. Thus, as an example, a locking mechanism embodying the present invention may as an operating unit be applied to 10 feet or 15 feet of a casting form length with a separate unit being disposed on the other side of Stich casting form. Where slabs of about 15 feet or 20 feet length are being cast in a casting form, it is possible for one workman to handle the locking and unlocking of the core positioning plates for the entire casting region. r1 "hus, the invention makes possible expeditious application to, and removal from, a casting form of a set of core positioning plates.

To reduce the number of separate plates per casting form required for different thicknesses of slabs, it is advantageous to arrange two positioning plates for two different slab types in back to back relation, thus makmg a dual plate unit to be handled. A complete set of For a complete description of the invention, reference will now be made to the drawings in conjunction with the specification. In the drawings,

FIG. 1 is a top plan view of an embodiment of the invention, a casting form being shown in position.

FIG. 2 is a side elevation on line 2 2 of FIG. l.

FIG. 3 is a section on line 3-3 of FIG. 1 on an enlarged scale.

FIGS. 4 and 5 are perspective details of the locking means for one core positioning plate half in unlocked and locked positions respectively.

FIG. 6 is a section on line y6 6 of FIG. 1.

FIGS. 7 and 8 are enlarged plan views in the unlocked and locked positions respectively of the mechanism for operating the locking means.

FIG. 9 is a section on line 9-9 of FIG. 7.

FIG. 10 is a section on line 10-10 of FIG. 8.

FIG. 11 is a section on line 111-11 of FIG. 1.

FIG. 12 is an enlarged sectional detail on line 12-12 of FIG. 8.

Casting form 10 may be of suitable construction such as, for example, disclosed in United States Pat. No. 3,023,477, issued March 6, 1962. Other casting forms which may be used are disclosed in United States Pats. No. 2,614,309, issued Oct. 21, 1952 and 2,758,353, issued Aug. 14, 1956, the latter disclosing a casting form having removable sidewalls. For convenience, a simple one piece casting form is illustrated such form having bottom 11 and sidewalls 12. Each sidewall may have an integral or detachable key forming member 13 extending the full length of the casting region for providing a grout key in the cast slab.

In the facility embodying the present invention, and for convenience, a casting form structure of predetermined width will be used. Casting forms proper of different widths may be used in the new facility, the structure of such casting forms having side extensions wide enough to t into the new facility even though the transverse width of the casting region portion of the casting form may be less than the maximum width of a casting form to be accommodated.

As is well-known, casting form 10 has end bulkheads 16 and 17 which accommodate prestressing strands 20 for the length of the casting region. Inasmuch as the bulkheads and arrangement of prestressing rods forms no part of the present invention, no detailed description thereof will be given. Reference is made to United States Pats. 2,299,111; 3,118,211; 3,202,394 and 3,207,829 for bulkheads and prestress strand handling means. In the use of a facility embodying the present invention, it is necessary for a casting form with bulkheads, prestressing strands and cores to be arranged.

Cores 24 of any desired shape and construction are provided and positioned in the casting form. Where cores having a transverse circular shape are used to provide longitudinal passages of generally circular section in the cast slab, then such cores may be made of suitable flexible material such as plastic or rubberized fabric inflated with air, this being disclosed in the prior patents previously identified. Where non-circular passages are to be provided, ditferent core constructions such as, for example, those illustrated in United States Pats. 2,977,658 and 3,101,519 may be used.

The details of the number of cores, structure of cores and shape are unimportant in connection with the present invention except that core positioning plates shaped to correspond to the core shape and arrangement must be used. The core shapes and core number and arrangement illustrated herein are exemplary for purposes of illustration.

In general, the facility illustrated in the drawings includes a rigid horizontal main frame having longitudinal channels 25 and 26 secured at the ends to cross channels 27 and 28. At spaced intervals along the length of the main frame are transverse tie plates 30. Disposed below the two ends of the main frame are stationary support pads 32 and 33 to which are secured vertically disposed channels 35 and 36 and sloping channels 37 and 38. Hydraulic lifts or jacks 40 and 41 rest on pads 32 and 33 below the main frame and carry support plates 42 and 43 upon which the main frame may rest. Additional intermediate supports and lifts may be provided. The entire main frame can be elevated by the lifts.

Plates 42 and 43 ordinarily are low enough so that when the main frame rests upon these plates, the elevation of the main frame will ordinarily be too low for use with a casting frame. In use the main frame and its associated structure (core positioning plates and locking means) is elevated high enough well above the top of any casting frame with which it is to be used. Vibrators 45 are disposed at various xed locations for operation on a casting form. The vibrators may be of any suitable type used in this art as, for example, illustrated in U.S. Pat. No. 2,927,418. No attempt is made to show electrical, air o1 hydraulic connections to lifts or vibrators, it being understood that such devices are properly energized when desired.

The normal level of the supporting surfaces for vibrators (usually such force is transmitted through heavy steel plates 46 upon which the casting form will rest) is low enough so that a casting form which has previously een cleaned, oiled, provided with cores located in bulkheads is Wheeled into position on suitable carts below the elevated main frame but above the vibrator support surfaces. Lugs 47 on plates 46 are provided to retain a casting form against lateral travel. After the casting form is lowered from the carts to the vibrator supporting surfaces, the entire main frame construction is lowered above the casting form with the plates to be described extending into the form deep enough to position the cores. The jbottom edges of the retainer plate handles will rest on the casting form. After everything is properly positioned, mix is poured into the form. In practice, the weight of the entire main frame structure and accessories including the core retaining plates will be somewhat greater than the upward force due to the buoyancy of the cores in the concrete and the upward buoyancy force may be about 75% of the weight of the entire main frame structure. This, however, may vary widely depending upon the depth and dimensions of the casting form. It is, of course, possible to adjust the downward force due to the weight of the main frame by the lifts below the main frame assuming part of the weight, the excess force due to the weight of the main frame being applied to keep the retainer plates down against the cores.

The relative proportions of the channel width of the main frame with respect to the channels of the casting frame have been somewhat exaggerated for the sake of clarity. In practice, the Width between channels 25 and 26 will be greater than the width of the casting form channels but the difference, as a rule, will be of the order of several inches.

Channels 25 and 26 on the main frame are similar for most of the structure involved so that, for convenience, channel 25 will 'be described in detail with the understanding that the description applies to channel 26 unless noted otherwise. Channel 25 carries at its web outer surface 55 (this being away from the channel flanges), as by welding, shelf 56 extended along the main frame.

Extending upwardly from shelf 56 and disposed against web surface 55 and welded to both are spacer blocks 58 each having slot 59 cut into the same to extend upwardly from the top of shelf 56. Slots 59 face away from web surface 55. The spacing between adjacent slots 59 along the length of channel 25 corresponds to the regions along the length of a casting form Where core retainer plates are to be disposed.

The width of each slot 59 (along the vform length) will be somewhat greater than the thickness of a core retaining plate handle portion (in this instance about 1% of an inch as an example). In general, slots 59 will be disposed at about 16 or 20 inch intervals, the exact distance depending upon various design factors.

Above the top face of each block 58 and welded to both the block and channel web are aligned tubular guide portions 61 and 62, there being guide portions corresponding to blocks 58 and slots 59.

For convenience, tubular guide portions `61 and 62 have spaced opposing ends 61a and 62a, each of which lies in a at plane, substantially perpendicular to support shelf 56 and to the length of the tubular guide portions. Opposed ends 61a and 62a of adjacent tubular guide portions 61 and 62 are spaced, from each other by a distance sucient to accommodate the thickness of the handle portion of a core positioner plate (in this instance at least of an inch).

Core retaining plate 65 has lower edge portion 66, upper edge portion 67 and handle portions 68 extending from opposite ends of such plate. Plate 65 is preferably of steel and is heavy enough (as an example 1% inch plate) so that the plate is sufliciently strong to perform the desired function. The body portion of plate 65, this being the portion between the inner ends of handles 68, is wide enough to extend between the opposite sides of a casting form. Bottom edge 66 of a core retaining plate is suitably shaped to cooperate with a desired arrangement of cores to be used in the casting operation. Top edge 67 of the core plate is active and can be used by removing and turning each core plate upside down to render the desired edge portion active. It is understood that core retaining plates 65, when properly positioned, are disposed at spaced intervals along the length of a casting form, all of the active edges of such plates being the same when used for casting a particular size slab.

Referring back to FIG. 4, core retaining plate handle portion 68 has its thickness (as an example 3A; inch) a bit less than the spacing between tubular guide portion ends 61a and 62a. The width of slots 59 will be somewhat greater than the thickness of handle portion 68.

Considering only the arrangement of tubular guide portions 61 and 62, core retaining plates 65 may be removed from or dropped into position in a casting form by having the ends of handles 68 and 69 slide down between spaced ends f tubular guide portions to lie in slot 59. The length of spacer block 58 between the top of shelf 56 and the bottom of tubular guide portions 61 and 62 will be at least great enough to accommodate the width of the handle portions of a core positioner plate. Thus in FIG. 4, handle portion 68 is suiciently narrow (the dimension perpendicular to support shelf 56) so that when handle portion 68 rests upon shelf 56, the upper edge of handle portion 68 will be below the bottom wall of tubular guide portions 61 and 62.

It will be understood that the locking parts of tubular guide portions 61 and 62 are those parts which terminate in ends 61a and 62a at each spacer block 58. Whether a tubular guide portion 61 or 62 extends for the full distance to the next core positioner plate location is immaterial. Thus, as an example, tubular guide portions 61 and 62 may each have a length of 4 or 5 inches and be disposed along the length of a casting form at spaced intervals so that proper registration between opposed ends 61a and 62a and a desired core positioning plate may be obtained.

Cooperating with the aligned lengths of tubular guide portions 61 and 62, is locking bar 73 having slots 74 at spaced intervals along the length thereof. Each slot 74 is dimensioned so that the width and depth of the slot will, in the proper position of locking bar 73, permit handle portion 68 to be moved upwardly past the tubular guide members and clear of the main frame so that in effect the entire core retaining plate may be removed from the entire facility, assuming that positioning plate 65 has its other handle portion free to be removed. The width of locking bar 73 is great enough so that at slots 74 there will be enough metal for bar 73 to retain its one piece character. Slots 74 in locking bar 73 are disposed at intervals so that, along the length of the entire facility, bar slots 74 can register with spaces between opposed ends of tubular guide member 61 and 62 when in unlocked position.

It is, of course, possible to have one continuous length of tubular guide and cut slots therein instead of having separate guide portions. However, the arrangement of separate lengths of tubular guide is easier to manufacture and is mechanically more desirable. Locking bar 73 is small enough in transverse dimensions for the bar to be quite loose in the tubular guide portions.

The locked portion is shown in FIG. 5 and shows slots 74 out of registry with the edge of handle portion 68. In this position, upward movement of each handle portion 68 along a casting form is prevented.

Means are provided for moving a desired length of locking bar 73 between locking and unlocking positions. The range of bar travel is limited so that locking bar 73 cannot be moved through a sufficiently great distance to an undesired locking position. Thus, locking bar 73 need only be moved a short distance (less than one inch) to cover the locking and unlocking range of travel. A desired length of bar 73 operating over a desired length of casting form can be operated by one power means such as an air cylinder or by manual means. In either case, it is desirable to have a limited range of travel for bar 73 between one locking and one unlocking position.

A simple manual control for locking bar 73 will now be described. Locking bar 73 has one end apertured at 79 for pivot pin 80, the axis of the pivot pin being vertical in the normal position of the main frame. Locking bar 73 is coupled by pivot pin 80 to link 81 pivoted at 82 to actuating arm portion 84 of bell crank 85 extending through a slot in the channel web and pivotally secured at 86 between angle pieces 88 and 89 rigidly secured to the inside surface 90 of the web of frame channel 25. Bell crank 85 has arm portion 92 terminating in actuating handle 93. The bell crank is adapted to have arm portion 92 and handle 93 extended along channel 25 between the anges when the locking bar is in a locking position. To maintain the bell crank in a locking position and prevent accidental movement of the bell crank to an unlocking position, aperture 9S is provided through horizontal portions of angle iron 88 and aperture 96 is provided through the handle portion 92 of the bell crank. A U locking lixture 98 has one leg which can pass through apertures 95 and 96 for keeping the handle locked. U fixture 98 can be pulled out whereupon handle 93 can be moved away from channel 25 and bell crank 85 will move locking rod 73 to a position where the positioning plates may be pulled out from the main frame. By proper design of the dimensions of link 81, bell crank 85, handle 93 when pulled to its outermost position will position locking rod 73 to a desired unlocking position.

While a casting form is being vibrated, substantially the entire weight of the frame and set of core retaining plates is borne by the casting form. Thus, the bottom edges of handle portions 68 of each core retaining plate will rest upon the top ange of a casting form. A particular set of core retaining plates will determine the level to which the active bottom portions of the plates will reach. Because of this, core positioning plates 65 are heavy enough for the load. After the casting form has been vibrated sufciently, the vibration is stopped and the main frame and core positioning plates are elevated above the casting form. The casting form is then picked up by carts and moved to a location where screeding occurs to fill in the voids caused by the removal of the core retaining plates.

The mix, after vibration has finished, is generally stiff enough so that removal of core retaining plates will not result in appreciable rise of cores. Sometimes cores may move up in response to their buoyancy after the removal of such core retaining plates but the movement is small, about 1/8 of an inch or less.

After a frame and a set of core retaining plates have been used and have been elevated free of a casting form and its contents, the retaining plates may be washed to remove particles of cement or mix in preparation for a new cycle of operation.

It will thus be evident that the general casting procedure set forth in the 2,299,111 patent previously identified is largely followed. The invention makes for a more eficient manipulation of core retaining members and makes it easier to change a set of core retaining plates for use with different core arrangements.

What is claimed is:

1. In a facility for casting elongated concrete slabs, where long cores must be positioned to provide ducts lengthwise of a slab, a main frame normally horizontally positioned and large enough to accommodate a slab casting form in horizontal position within the frame outline, a set of separate core positioning plates for use in said main frame, each plate being at for disposition in said casting form transversely to the form length with each plate extending edgewise into said casting form during the operation of said facility, means on said casting frame for supporting said set of plates in spaced laterally offset parallel relation, means operative on said set of plates for selectively simultaneously locking each of said plates into position against upward vertical edgewise movement out of each of said frame or unlocking said plates for removal from said frame, means for vertically positioning said supporting means and said plates over casting form whereby said core positioning plates may extend into said casting form, vibrating means adjacent said casting form to settle concrete mix therein and remove air therefrom, said set of core positioning plates adapted to be movable vertically as a unit into position in said casting form prior to casting form vibration and removable therefrom after casting form vibration has been accomplished.

2. The construction according to claim 1 wherein said core positioning plates have handle portions at each end adapted to extend over the top edges of said casting form.

3. The construction according to claim 2 wherein said supporting means has support shelf means upon which lower edges of said handle portions can rest, and wherein said locking means for each plate includes first slotted members for cooperation with each handle portion of each said core positioning plate, said slotted members being spaced along the frame length and wherein cooperating slotted members are longitudinally movable with respect to the rst named slotted members, two slots being adapted to register for unlocking the handle portion of each said core positioning plate, each said core positioning plate being locked into position against withdrawal when said slotted members are out of registry with each other and means for moving all of said movable slotted members simultaneously to lock or unlock said set of core positioning plates.

4. The construction according to claim 3 wherein said rst slotted members for each plate consist of a plurality of aligned tubular guide members having opposed ends to define a slot and wherein the movable slotted members are longitudinally movable bars having slots which can register with the slotted tubular guide member slots to define an unlocked position, said slotted bars being movable so that their slots do not register with the tubular guide member slots for locking said core positioning plates against removal.

5. The construction according to claim 4 wherein said tubular guide members have non-circular sections, said bars having correspondingly shaped sections to prevent said bars turning on their axis within said tubular guide members and means engaging an end of each said bars for moving the same through a limited range of travel to deiine definite plate locking and unlocking positions.

6. The construction according to claim 1 wherein each said plate has at least one shaped edge for the body portion to cooperate with casting form cores for positioning the same when such plate lies in a vertical plane across said casting form.

7. The construction according to claim 6 wherein each said body portion has an additional shaped edge on the other side of a line extending between said handles, the active edge being selected by turning the plate so that the active edge extends into the casting form during use.

References Cited UNITED STATES PATENTS 2,949,657 8/1960 Anson 249-65 X 3,189,955 6/1965 Zavertnik et al. 162-243 X 3,407,458 10/1968 Reckman et al. 2541 ROBERT D. BALDWIN, Primary Examiner U.S. C1. X.R. 

